Standing wheelchairs, including both motorized and non-motorized versions having many different designs, are known in the art. These known standing wheelchairs are generally designed with the center of mass in the center of the wheelchair while the user is in the seated position. As the user is moved into the standing position, he or she is moved toward the front of the wheelchair, thus changing the location of the center of mass. To counterbalance the weight of the user at the front of the wheelchair when in the standing position, many wheelchairs are designed with a large amount of weight in the rear to prevent tipping of the wheelchair. Other standing wheelchairs are designed so that when the user is in the standing position, the footrest portions of the wheelchair contact the ground and in this manner prevent tipping of the wheelchair. However, when the user is moved into the standing position at the front of the chair, most of the user's weight is located at the front of the wheelchair, resulting in a "tippy" feeling in which the user feels that the wheelchair is about to tip over. To a person with a disability who must rely upon the wheelchair for mobility and support, and who utilizes the standing capabilities of the wheelchair to lead a more productive and independent life, this "tippy" feeling is an extremely uncomfortable sensation and detracts from the user's ability to fully lead a productive and independent life.
A common problem with all standing wheelchairs is the occurrence of shear which is created while the lifting mechanism is in motion. Shear is due to the offset of the user's knee joint and the pivot point of the seat assembly, with the greater the distance between these two points, the greater the shear and the resulting amount of discomfort, often times causing skin abrasions. Over time, the resulting skin abrasions can ultimately lead to the development of pressure sores, which are a significant problem for many people with disabilities. Therefore, a standing wheelchair should reduce the distance between the user's knee joint and the pivot point of the seat of the wheelchair as much as possible, in order to reduce the amount of shear that is created during movements between the seated and standing positions.
Existing standing wheelchairs also position a user at an angle of up to 27 degrees from a fully vertical standing position. This compromised posture prevents the user from reaching objects positioned at a greater distance, by reducing the distance of the user's reach, thus decreasing the user's independence. A proper standing posture is also important for the health and lasting comfort of the user.
Further, people often shy away from users of wheelchairs since wheelchairs are in general unapproachable, intimidating, ugly and awkward, utilizing intricate and complicated mechanical parts and systems which give the wheelchair a distracting appearance. Therefore, a standing wheelchair that is visually appealing, and which eliminates, or hides from view, many of the intricate mechanical components would be beneficial.
A standing wheelchair should also be adjustable so as to be able to accommodate different users who are each sized differently. Further, as with most machines, a standing wheelchair should be simple in design with the minimum number of parts, so as to reduce assembly time and reduce the number of parts that could potentially break down, need maintenance or repair.
Therefore there exists a need for a standing wheelchair that reduces shear on the user when moving between the seated and standing positions, as well as reduces stress on the lower body of the user, improves the reaching capabilities of the user while providing lasting comfort to the user in the standing position, adjusts so as to accommodate different users, and is simple in design with a reduced number of parts and systems. In addition to the above requirements, the standing wheelchair should be designed so as to be aesthetically appealing.